add_filter() thows error | Removing the admin bar

Question

 Fatal error: Call to undefined function add_filter() in /home/paperme/foo.com/wp-includes/functions.php on line 3647

I got this error when adding this snippet to the end of functions.php

I was told this snippet would successfully remove the admin bar.

/**
 * Added by Chris - 10/03/2012
 */


function hide_admin_bar_from_front_end(){
  if (is_blog_admin()) {
    return true;
  }
  return false;
}
add_filter( 'show_admin_bar', 'hide_admin_bar_from_front_end' );

Answer 1

Never touch anything in wp-includes. Use the functions.php in your theme or a custom plugin.